Conventionally, as an intermediate connector, or a so-called interposer, a technique disclosed in Patent Document 1 has been known, for example. In Patent Document 1, a multilayer wiring board as an intermediate connector is disclosed. With regard to the multilayer wiring board, the Patent Document 1 discloses a technique of forming a multilayer wiring board by laminating a plurality of unit wiring boards including an insulating layer, a wiring layer, and a via hole conductor.